Apparatus and method for rolling, forming, and welding



June 22, 1937. .1. L. ANDERSON APPARATUS AND METHOD FOR ROLLING, FORMING, AND WELDING Filed June 27, 1934 4 Sheets-Sheet l W EV ENTOR W ATTORNE June 22, 1937. J. ANDERSON 2,084,375

APPARATUS AND METHOD FOR ROLLING, FORMING, AND WELDING Filed June 27, 1954. 4 Sheets-Sheet 2 f EVENTQR ATTORNE H ...H.. .M.H. X. ..HIH.H.H.W H MuH m 3 m Q 5 i if 1-- mn .H.

T: IE i Ea L Q W2 a JflflliJW E mm Q- {Kiln r T 2 m m 3 i Q o June 22, 1937. J. L. ANDERSON 2,084,375

APPARATUS AND METHOD FOR ROLLING, FORMING, AND WELDING Filed June 27, 1934 4 Sheets-Sheet 3 ANVQTOR BY Z ATTORNEY aFume 22, 1937. J, L, ANDERSON 2,084,375

APPARATUS AND METHOD FOR ROLLING, FORMING, AND WELDING Filed June 27, 1954 4 Sheets-Sheet 4 56 j '52 65 v a 69 as a;

ATTORNEY Patented June 22, 1937 APPARATUS AND METHOD FOR ROLLING FORIVIING, AND WELDING James L. Anderson, Cluster, N. 1.,

Air Reduction Company, Incorpo York, N. Y., a corporation of New York Application June 27, 1934, Serial No. 732,593

into the seam and rotated at plated the produc many years ago were of the order 0 stated, final rolling spee order, the development high speeds. With this inventi can be welded at these high An apparently making of welds at final ro the time element, and of heat transfer by con of the tube edges.

It is an object of method and apparatus welded pipe or tube in continuous opera made under this inven weld and of better qua the body of the tube.

One of the objec fore, to provide a met welded pipe or tube can be made from a operation. While the use 0 limited to the production 0 it is an advantage herein disclosed th can be made at excee the speeds at which skelp may skelp rolling pass. possible to effect progressive, welding of pipe rolling of the sk knowledge, the in factory to make w 9 Claims- In the production of the strip metal or skelp from which welded tubes are made, a piece of metal, which may be a billet or a bloom, or even an ingot, is heated in a furnace to the temperature for rolling, and is then withdrawn from the furnace and put through a number of rolling passes each of which effects a reduction in the thickness of the material, so that it emerges from the last pass with the correct gauge for the size of tube to be manufactured. For convenience, the term billet" will be used in this specification in a general sense, as meaning any relatively short and massive starting piece from which skelp may be rolled at a single furnace heat.

Since the material is elongated as its thickness is reduced, the speed of travel of the metal increases with each successive rolling pass, and

the skelp comes from the final pass at high speed. The skelp may be cut to desired lengths by a flying shear located at the end of the skelp mill, or the skelp may be wound into rolls. In either case the metal must later be re-handled and reheated to produce a welded pipe or tube.

In some plants, skelp from the last rolling pass goes directly into a forming mill, which bends the hot skelp into an open-seam tube, the result being that the billet is changed into a completely formedopen-seam tube in a continuous or substantially continuous operation.

By an open-seam tube in this specification is meant a fully formed but-unwelded tube in which the opposing seam edges are adjacent one another, or in contact.

It has long been recognized that great economies in space, heat, time, and handling and large increase in production could be effected if the heated billet could be rolled, tubularly formed, and welded in a continuous operation. Various plans have been proposed, but so far as I am aware no satisfactory method has been devised for producing welded pipe or tube in such a manner.

In modern rolling mills the skelp comes from the skelp mill at speeds of 600-1000'feet, or more, per minute. An open-seam tube can be formed at this speed, or at higher speeds, but even though the tube issues from the forming mill with much of the original heat left in it, the addition, at this high speed, of heat necessary to raise the edges to a welding state has been a difficult if not unsolved problem. The plans which have been proposed for heating fast-moving tube edges include electrical resistance heating; heating by a seamwise-extended system of gas flames, or electric arcs; and heating by friction discs extending rated, New

with opposing edges ans contemand were v rolling speeds 00 feet per minute. As 5 re now of a different being in the direction of on hot-rolled skelp high speed. Such pl tion of pressure w ds insurmountable difficulty to the lling speed has been welds the rate duction through the metal this invention to provide a by which high-quality a heated billet tion. Pipe and tube can be tion with no oxide in the lities in the weld than in is made from of the process It has never Other aspects of th combined forming or ben tubular form, higher speeds than are applicable to the man from skelp already'ma separate operation.

In the preferred mode 0 invention the metal is passes until it is reduc e invention, ding of the skelp to the f the edges at much would otherwise be possible,

and Welding o ufacture of pipe or tube ufactured by previous,

f application of the gh rolling mill ed to the gauge of skelp d through a forming mill. high temperature flames,

oxy-acetylene mixture, ted directly against the The flames are applied asses of the forming the first forming pass, and 55 and the skelp strip is fe The skelp is heated by preferably those of an the flames being projec edge faces to be welded. to the edge faces mill and ahead of even to the fiat skelp, portioned with respect the skelp that the edge faces are heated to a welding condition by the time they come together in the final forming pass.

By the use of an oxyacetylene flame mixture the skelp edges can be heated to welding state or to fusion at high rates of travel of the skelp. Other fuel gases or vapors may, however, be employed. The oxygen supplied to the flame mixture is preferably commercially pure oxygen though mixtures of fuel gas and oxygen-enriched air or the like may be used. With several stages of heating, it is possible to employ mixtures of diiferent compositions in different stages, and with a sufficiently extended edge heating system a mixture of air and fuel gas may be utilized in one or more stages.

Other features and modes of application of the invention will become apparent from a consideration of the following description and of the accompanying drawings, wherein:

Fig. 1 is a diagrammatic plan view illustrating the relation of apparatus and the steps of the process of this invention.

Fig. 2 is a top plan view, on an enlarged scale, of a portion of the apparatus shown in Fig. 1.

Fig. 3 is a side elevation of the apparatus of Fig. 1, but showing only the last stand of the skelp mill.

Figs. 4-6 are sectional views through the skelp showing its shape at various stages during the forming step. i

Figs. 7 and 8 are enlarged sectional views of the heating retorts through which the skelp passes when fiat and partially formed, the sections being taken on the lines 1'! and 88 of Fig. 2.

Figs. 9 is an enlarged sectional view on the line 9-9 of Fig. 2.

Figs. 10 and 11 are enlarged detail views, partly 'n section, showing the rollers and mandrel illustrated in Fig. 9. l

Fig. 12 is a reduced longitudinal sectional view of one of the torches shown in Fig. 1.

Figs. 13 and 14 are enlarged sectional views on the lines I 3-I 3 and I I-I4, respectively, of Fig. 2. I

In a continuous rolling, forming, and welding operation, such as illustrated in Fig. 1, a heated billet I0 is drawn from a furnace II and put through the passes of a reducing mill I2, which reduces the billet to an intermediate strip. From the last pass of the reducing mill I2 this strip is transferred into a first stand I4 of a skelp mill I5. The flexible metal strip is indicated by the reference character I1, the skelp and partially-formed tube by I1, and the welded tube by II". The metal strip I1 is threaded back and forth through the successive stands of the skelp mill I5, the thickness of the strip being reduced in each stand. This mill arrangement is illustrative. All stands of a skelp mill may be in line, or in line also with preliminary reducing stands in a straight-through operation.

Besides the first stand I4, the skelp mill shown in Figs. 1 and 2 has an intermediate stand I9 and a last stand 20, besides which there may be other stands or passes.

Passage of the metal strip I I through the last stand 20 of the skelp-milleifects the final reduction in thickness necessary to produce a skelp of the desired gauge for the tube. The reduction in the thickness of the metal in each rolling pass increases the length of the strip and therefore the the heating being so proto the speed of travel of...

lineal speed. The skelp II' issues rapidly fron the final rolling pass through the last stand 20 The skelp mill I5 is driven by a motor 22. A forming mill comprising stands 24 and 25 ir line with the last stand 20 of the skelp mill receives the skelp from the final rolling pass.

The rollers of the forming stands' 24 and 25 are driven from the motor 22 through gearing 26.

Before entering the final rolling pass 20, the rapidly moving hot strip I1 passes through a retort 28 in which the edges of the strip are heated, preferably by oxyacetylene flames, though other flame heating means may be employed. A guide 29 at the entrance end of the retort 28 guides the end of the strip II into the retort 28 and rolling stand 20 when the strip is first threaded through the skelp mill. There are similar guides at the entrances to the other rolling stands I4 and I9.

The flames in the retort 28 increase the heat of the skelp along its edges, in addition to which the hot products of combustion that sweep across the upper and lower surfaces of the strip sustain the temperature at the edges by reducing the temperature gradient from the edges to the interior of the strip. A useful effect of heating the strip in this manner before it goes through the final fiat rolling pass is to eliminate a part of the mill scale then present on the strip and keep it from being rolled into the skelp surfaces.

Between the forming pass 24, the skelp travels through a retort 30, which is similar to the retort 28, and

final rolling pass 20 and the first further increases the temperature of the skelp edges. I

As the skelp bends from its flat condition in the retort 30 to the partially formed condition assumed in the first pass 24 of the forming mill, it travels through a retort 3I which has guides and burners shaped to conform to the change in the cross-section of the skelp as it bends under the influence of the first forming pass 24 or breakdown pass. It is not necessary to the invention that the forming be done in rolls. A forming die can be used in one or more stands, but rolls are required for feeding the metal through such a die when used in a continuous operation.

In the forming pass 24 the skelp is confined between a grooved roller 32 (Fig. 2) and a roller 33 which has a convex face extending into the groove. A section through the partially formed skelp, as it leaves the forming pass 24, is shown in Fig. 5. The center portion of the skelp is bent into an arc of degrees and the side portions extend upward substantially parallel to one another. The forming in this first pass 24 may be less than that shown in the drawings, that is. the are into which the skelp is bent may be less than 180 degrees of the width of the skelp. The amount of formand may extend across more or less ing which should be imparted to the skelp in the first forming pass is largely dependent on the number of subsequent passes in the forming mill. There may be several forming passes, between certain of which the skelp may be bent to a greater degree than is shown in the drawings. Thus, the side portions of the skelp may slope inward instead of being parallel, but it is a feature of the invention that the edges of the partially formed skelp be widely spaced and so disposed that the heating flames canbe' applied directly against. the edge faces.

This partially formed skelp section proceeds through a retort 35, which is shaped to receive the skelp in the form with which it leaves this stocks are connected to forming pass 24. The forward and rearward ends of the retort 35 are shaped to extend partially between the rolls of the forming mill in order to obtain the greatest possible length for the retort 35 within the distance between the stands of the forming mill.

The edge faces 'of the skelp are finally purified and are heated to surface fusion in the retort 35 and while in this state are brought together in the final forming pass to cause the clean fused metal on the edge faces to unite and form a strong and perfect weld. Welded tubes made in this manner can be bent sharply or flanged without breaking the weld, and can be drawn to reduce the diameter and/or wall thickness. This latter operation results in a severe working of the metal and is employed to produce tubes of great strength.

If especially high-grade pipe or tubing should not be required, theinvention may be employed to produce pressure welded pipe or tubing of uniformly good quality and with great economy of heat. The economy of heat'is made possible by the direct manner in which the heat is applied to the edges and by the uniform heating which makes it unnecessary to raise the temperature of some parts of the skelp higher than necessary while bringing adjacent portions to a welding state. When the edge faces are not brought to surface fusion, it is necessary to adjust the rolls in the final forming pass 20 so that the edges of the skelp are brought together under considerable pressure, or to employ a closing die or bell for obtaining such pressure.

All of the added heat for raising the skelp edges to surface fusion or to a welding state may be put into the edges in the retort if the distance is made long enough, but in a plant such as illustrated retorts between three or more mill passes are more effective and permit of very high speeds. The torches and retorts applying heat to the skelp in stages as it travels between successive mill passes makes it possible to bring the edge faces to surface fusion, notwithstanding speeds of travel of the skelp as high as a thousand feet per minute,

or higher.

fuel gas are brought together by suitable mixers in the stocks 4|, or in stems 42 by which the the burner block, and the mixed gases distributed by longitudinal passages in the blocks, from which they issue through jet orifices. The flame system directed against the edge faces of the skelp may be a single or double row of closely spaced jets, or staggered jets, or one or more ribbon flames.

The retort 30 comprises retort bodies 44 and 45 secured to a supporting base 46 on opposite sides of the skelp. The supporting base extends from the final stand of the rolling mill, as shown in Fig. 3. The retort bodies 44 and 45 are held in position on the base 46 by screws 41 which extend through slots 48 (Fig. 2) in the retort bodies. These slots permit the retort bodies to be moved closer or further apart to accommodate skelps of difierent width.

Referring again to Fig. 7, each retort body comprises upper and lower sections 49 and 50 hollowed to form a chamber 5| for the burner block 38, and formed with mating portions 52 and 53 at the front and rear ends. Shims 54 between these mating portions establish the proper vertical distance between the surfaces 55 and 56 of the retort sections which overlap the upper and under-surfaces of the margin of the skelp. The height of the skelp passages through the retort is slightly greater than the thickness of the skelp so that it can pass through these passages with little friction, but the surfaces 55 and 56 serve as guides to keep the skelp substantially flat until it reaches the end of the retort and begins to bend under the pull from the rollers 32 and 33 of the first forming pass.

The shims 54 serve as side guides when the front end of the skelp passes into the retort, but after the skelp has entered the rollers32 and 33 of the first forming pass ordinarily no side guides are necessary, because these rollers have a speed along their median lines slightly greater than the peripheral speed of the rolls in the final rolling pass so that the skelp is under some tension and is held in a central position as it passes through the retort 30.

Water or other cooling fluid circulates through passages 58 to prevent the retort from becoming overheated. The cooling fluid enters and leaves the passages 58 through hose or pipe connections (not shown) The retort, and likewise the other retorts, are preferably made of bronze, or abrasion-resisting iron or steel, or the surfaces which contact with the skelp may be copper-plated so that they will not tend to stick to the skelp and wear excessively The burner blocks 38 are clamped against bosses 60 on the lower sections 50 of the retort by screws 6| extending through slots in the burner blocks. The heads of the screws 6| are high enough to extend through openings in the upper sections 49 so that a wrench can be conveniently applied to these screws to release them when the positions of the burner blocks in the retorts are to be changed. When using oxyacetylene flames, the jet faces of the burner blocks are positioned close enough to the skelp so that primary combustion takes place immediately adjacent the edge faces of the skelp. The products of the primary combustion, containing reducing gases, blanket the edges, and the final products, at a temperature twice or more the skelp temperature, sweep inward over the upper and under surfaces of the skelp, heating them so that heat loss from the edges by conduction into the body of the skelp is minimized. By the action of the heat and of the gases, in this and in the other retorts, the edges are deoxidized and purified and any gas pockets in the edge metal are substantially eliminated, and the highly heated skelp is protected from oxidation by contact with the air.

The surfaces 55 and 5B confine the products of combustion and cause them to flow across the upper and lower faces of the skelp. These surfaces may be grooved to provide more space for the flow of gases from the retort. Air for burning the products of the primary combustion enters the chambers 5| around the sides and ends of the burner blocks 38. The retort bodies can be made with no space for the entrance of air around the torch blocks, in which case the oxygen for the secondary combustion may be supplied through clamped against bosses on auxiliary Jets opening into the chambers ll. Much of the ongen necessary to support the secondary combustion may be supplied in the mixture fed through the flame jet openings of the torch blocks. when the hot skelp is passing through the retort, combustion becomes substantially complete within the restricted retort chambers, little or no visible flame issuing therefrom into the atmosphere.

Fig. 8 is a sectional view of the retort 88. This retort comprises side blocks 88, 88, which are secured to brackets 88 (Fig. 3) extending from the forming mill stands 24 and 28. The side blocks are shaped at their ends to extend part way between the upper and lower roll of each stand.

Referring again to Fig. 8, a center block 81 is located between the side blocks 88 88, and held spaced from the side blocks by transverse supports 88 which are fastened to the center block 81 and side blocks 88, 88 by screws 88. With the blocks in the assembled relation shown in Fig. 8 they enclose a skelp chamber 18 and torch chambers 1| opening into the skelp chamber.

The skelp chamber 18 has a cross-section simi-- lar to that of the skelp 11 as it comes from the forming pass 28, but is large enough to allow sufiicient space for the flow of the products of combustion downward away from the torch chambers and across the surfaces of the partially formed skelp. The most intense heat is applied directly to the skelp edges, and the products of combustion, hotter than the skelp and flowing over its surfaces, heat the body of the skelp. The high temperature gases acting on the edges reduce and purify the edge metal, so that when the edges are brought together and united,'the

weld that is made is free of oxide, of exceptional strength and without defects. Furthermore, the

reducing action extends over the outer and inner surfaces of the skelp. By bathing the skelp surfaces, generally, as it passes through this retort, and also as it passes through preceding retorts, with hot gases more or less reducing in their action, not only is the skelp as a whole protected from oxidation during these stages, but also mill scale or oxide which formed on the skelp in its progress through the rolling mill passes is virtually eliminated. The remainder of such scale is in the form of a loose powder. The elimination of mill scale by the flame gases is aided by the loosening of the scale by the bending of the skelp in the forming operation.

The products of combustion which pass across the outside. surface of the skelp escape from the retort through slots 12 in the side blocks and through the space between the side blocks at the bottom of the retort. A conduit 18 in the center block 61 communicates with the skelp chamber 18 through slots 18. The products of combustion flowing across theinside surface of the skelp escape through the slots 18 and conduit 18. A' suction pipe 18 (Fig. 9) draws the gases out of the conduit 19.

Referring again to Fig. 8, torches l8 and 18 are the center block 81, by screws 88 which extend through slots in the side blocks for convenient access when the torches are to be adjusted in the torch chambers to regulate the spacing of the flame jets with respect to the edge faces of the skelp. This movement of the torches permits the retort to be used with skelps of slightly difl'erent width. Oxygen for the secondary combustion is supplied from a conduit 82 in the center block; This conduit communicates with the torch chambers through slots .88.

Air for secondary combustion is aspirated around the sides of the torches l8 and I8, but the upper sides of the torch chambers may be completely closed and all of the oxygen for the secondary combustion supplied under pressure through the slots 88 or similar es in the side blocks or in a cover extending between the side blocks, or some of the oxygen for the secondary combustion may be supplied through such passages and some through the flame Jet oriflces of the torches.

The side blocks 88, 84, are cooled by liquid flowing through passages 88, 88'. The center block 81 is cooled by liquid flowing in, a cooling chamber 88, best shown in Fig. 9.

The torches l8 and 18 are similar to the torches in the retort 88, with the exception of a slight curve at the ends of the torches l8 and I9 shown in Fig. 2. This curve of the torches enables them to follow the edges of the skelp as they move toward each other when approaching the final forming pass.

The skelp edges come together in the bite of rolls 88, 81 in the stand 28 to complete the forming operation and produce a welded pipe or tube. "The weld is preferably rolled down immediately between the upper roll 88 of the final forming pass and a roller 88 (Fig. 9) inside of the tube. The roller 88 is supported by a roller 89 which bears against the bottom of the tube. These rollers 88 and 89 have their axes on the center line of the rolls 88 and 81, and are held against movement lengthwise of the tube by axles which extend from both sides of the rollers into slots in the bifurcated end of a mandrel 9|.

An end piece 92 is fastened to the mandrel between the bifurcations. This end piece follows the curve of the roller 88 above the axle of the roller and limits the movement of the roller in the vertical slots of the mandrel so that the roller axles can not come out of the slots when the roller is not in a tube. The end piece 92 extends part way under the lower roller 89 and prevents it from dropping out of the mandrel slots when not supported by a tube.

The mandrel 9| is connected, by pins 94, at its forward end, to an extension of the center block 61. A conduit 95 through the ters with a passage 98 which leads to the cooling chamber 88 of the center block 61. Water is discharged on the rollers 88 and 89 from the conduit 98 to cool the rollers.

The upper roller 88 is crowned and the radius of the crown is the inside radius of the pipe, as shown in Fig. 10. The lower roller 89 has a similar crown except for a. center groove 91 which is provided to increase the area of bearing contact between the rollers 88 and 88.

Fig. 12 is a longitudinal sectional view of the torch 18 showing the chamber 88 from which the fuel and oxygen mixture is discharged through the jet openings 98. The torch is cooled by the circulation of water through conduits I88 (Figs.

8 and 12). The gas is supplied to the chamber 98 through a stem I82, which corresponds with the stems 82 of the torches shown in Fig. 7.

Figs. 13 and 14 are tranverse sectional views through the retort 8|. This retort is supported by the base 88 and has blocks I88 which guide the skelp when the forward end of the skelp first enters the retort. A center block I88 is held over the skelp by transverse supports I88.

- The retort 8| comprises retort bodies I88 and I89, which are illustrated diagrammatically in Figs. 13 and 14. These retort bodies are similar mandrel 9| regisin construction to the retort bodies It and 45 shown in Fig. 7, except that the retort bodies I and I09 and their torches IIO are warped to follow the edges of the skelp as the skelp bends from its flat condition in the retort 30 to its substantially U -shaped contour in the bite of the rolls 3! and 33. Passages for cooling liquid and other details shown in the retort bodies in Fig. 7 are omitted in the diagrammatic illustration of Figs. 13 and 14.

The blocks I04 and center block I05 confine the products of combustion which'issue from the retort bodies I00 and cause these products of combustion to flow over the surface of the skelp. There are grooves H2 in the faces of the blocks I04 and center block I05. The blocks I04 are separated to provide a slot 3 between them and have passages IIl recessed in their opposing side faces and bottom faces for the es-.- cape of products of combustion which flow across the bottom face of the skelp. The center block I05 has passages I I5 and I It for the escape of the products of combustion which flow across the top surfaces of the skelp.

The invention has been described as applied to the manufacture of pipe or tubing from a billet in a continuous operation, but it will be understood that certain features of the invention are applicable to the manufacture of pipe or tubing from preheated skelp or even from cold skelp. The invention is not limited to the embodiment illustrated, and features of the invention may be used without others.

I claim:

1. The combination with a rolling mill which rolls metal toa flat skelp, of tube forming ap-' paratus into which the skelp passes as it comes from the last stand of the rolling mill, a plurality of roll stands in said forming apparatus, and means for raising the edge faces of the skelp to a welding state by the time they come together in the final forming stand while traveling at the speed of delivery of the skelp from the rolling mill, said means comprising retorts located along the run of the skelp or partially formed tube between successive roll stands through which the metal passes, and devices in the retorts for projecting intense heating flames directly against the longitudinal edge faces to be welded.

2. Apparatus for making welded tubes from a heated billet in a continuous operation, said apparatus comprising a rolling mill in which the billet passes through successive roll stands and is worked into a fiat skelp, a forming mill beyond the last stand of the rolling mill in position to receive the skelp as it comes from the rolling mill, at least two forming passes through which the skelp travels successively in the forming mill, and heating retorts constructed and arranged to project flame jets directly against the edge faces of the skelp to bring the edges to a welding condition prior to their passage through the last forming pass, said retorts being located between several successive millpasses so that the metal is subjected to the working of one or more roll stands during the heating of the edge faces.

3. A continuous process for making a welded tube from a heated billet, which process comprises rolling the billet to a flat skelp, forming the skelp as it comes from the last rolling step,

raising the temperature of the edge faces of the skelp to surface fusion during the forming step by projecting flame jets directly against the edge faces to be welded, and bringing said edge faces together during the forming step while in a state of surface fusion.

4. A continuous process for making a welded tube from a heated billet, which process comprises rolling the billet to a fiat skelp, forming the skelp in at least two forming passes immediately after the final rollin pas and while the metal is still at a high temperature, increasing the heat of the edge portions of the skelp by projecting gas jets directly against the edge faces to be welded as they travel between the forming stands, and proportioning the heating effect of said jets and the speed of travel so that the jets raise the edges to a welding state just ahead of the final forming stand.

. 5. In a continuous process in which a billet passes progressively through a rolling mill and a tube forming mill, each of which includes a plurality of roll passes, the improvement of raising the temperature of the longitudinal edge faces of the metal during their travel between some of the last roll passes by projecting flame jets directly against the edge faces, applying said flame jets to the run of metal between several roll stands so that the metal is subjected to the working of one or more roll stands during the heating of the edge faces, and proportioning the heating ofthe fiame jets to the speed of travel of the edge faces so that said edge faces are heated to a welding condition by the time they are brought together in the final forming pass.

6. The method of manufacturing pipe and tub-- ing from a heated billet which comprises rolling the billet to a fiat skelp, progressively forming the skelp into a tube immediately after the final rolling step and as a continuous operation with the final rolling step, and bringing the edge faces of the tube to a welding condition during the formingof the tube by projecting heating flames directly against the edge faces to be welded.

'I. A method of making welded pipe and tubing from a skelp traveling at the speed at which such skelp is discharged from the final pass of a rolling mill, said method including operating on the metal at two regions spaced along the length of the skelp to form the metal progressively into a tube, bringing the edge faces of the rapidly moving skelp to a welding condition during its travel between said regions by projecting high temperature flame jets directly against the edge faces to be welded, and protecting the heated skelp from oxidation by causing the products of combustion of the flame jets to flow inward from the edge faces and blanket the surfaces of the partially formed tube.

8. A method of making welded pipe or tubing from fiat, heated skelp traveling at high speed, including forming the skelp by bending forces applied in at least two regions spaced longitudinally along the skelp, and bringing the edge faces together with the final bending force, and raising the edge faces of the rapidly moving skelp to a welding condition during the forming of the skelp by projecting intensely hot flame jets di-' rectly against the edge faces to be welded to heat said edge faces substantially uniformly across their width between the regions where said bending forces are applied,- and so proportioning the heating and the speed of travel that the edge faces are heated to a welding condition by the. time they reach the region where the final bending force is applied.

to be welded to heat mid faces substantially unitormly across their width, end so proportioning the heating and the speed of travel that the edge faces are heated to a welding condition before they reach the final 1' rming pen.

JAIIIB L. ANDERSON. 

